Selection of Observation Position and Orientation in Visual Servoing with Eye-in-vehicle Configuration for Manipulator

2019 ◽  
Vol 16 (6) ◽  
pp. 761-774
Author(s):  
Hong-Xuan Ma ◽  
Wei Zou ◽  
Zheng Zhu ◽  
Chi Zhang ◽  
Zhao-Bing Kang
Keyword(s):  
Visual Servoing ◽  
Observation Position ◽  
Position And Orientation ◽  
Vehicle Configuration ◽  
Selection Of

scholarly journals Visual Servoing of a Moving Target by an Unmanned Aerial Vehicle

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5708
Author(s):  
Ching-Wen Chen ◽  
Hsin-Ai Hung ◽  
Po-Hung Yang ◽  
Teng-Hu Cheng
Keyword(s):  
Visual Servoing ◽  
Feature Vector ◽  
Field Of View ◽  
Control Input ◽  
Predictive Controller ◽  
Aerial Vehicle ◽  
Position And Orientation ◽  
Rotational Motions ◽  
And Performance ◽  
Traditional Image

To track moving targets undergoing unknown translational and rotational motions, a tracking controller is developed for unmanned aerial vehicles (UAVs). The main challenges are to control both the relative position and orientation between the target and the UAV to within desired values, and to guarantee that the generated control input to the UAV is feasible (i.e., below its motion capability). Moreover, the UAV is controlled to ensure that the target always remains within the field of view of the onboard camera. These control objectives were achieved by developing a nonlinear-model predictive controller, in which the future motion of the target is predicted by quadratic programming (QP). Since constraints of the feature vector and the control input are considered when solving the optimal control problem, the control inputs can be bounded and the target can remain inside the image. Three simulations were performed to compare the efficacy and performance of the developed controller with a traditional image-based visual servoing controller.

Multi-cameras visual servoing for dual-arm coordinated manipulation

Robotica ◽  
2017 ◽  
Vol 35 (11) ◽  
pp. 2218-2237 ◽  
Author(s):  
Jiadi Qu ◽  
Fuhai Zhang ◽  
Yili Fu ◽  
Shuxiang Guo
Keyword(s):  
Visual Servoing ◽  
Field Of View ◽  
End Effector ◽  
Visual Constraints ◽  
Position And Orientation ◽  
Dual Arm Robot ◽  
Pose Alignment ◽  
Alignment Errors ◽  
Object Features ◽  
Dual Arm

SUMMARYAlthough image-based visual servoing (IBVS) provides good performance in many dual-arm manipulation applications, it reveals some fatal limitations when dealing with a large position and orientation uncertainty. The object features may leave the camera's field of view, and the dual-arm robot may not converge to their goal configurations. In this paper, a novel vision-based control strategy is presented to resolve these limitations. A visual path planning method for dual-arm end-effector features is proposed to regulate the large initial poses to the pre-alignment poses. Then, the visual constraints between the position and orientation of two objects are established, and the sequenced subtasks are performed to attain the pose alignment of two objects by using a multi-tasks IBVS method. The proposed strategy has been implemented on a MOTOMAN robot to perform the alignment tasks of plug–socket and cup–lid, and results indicate that the plug and socket with the large initial pose errors 145.4 mm, 43.8○ (the average errors of three axes) are successfully aligned with the allowed pose alignment errors 3.1 mm, 1.1○, and the cup and lid with the large initial pose errors 131.7 mm, 20.4○ are aligned with the allowed pose alignment errors −2.7 mm, −0.8○.

scholarly journals Topology Optimization of Structures Made of Discrete Geometric Components With Different Materials

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Hesaneh Kazemi ◽  
Ashkan Vaziri ◽  
Julián A. Norato
Keyword(s):  
Topology Optimization ◽  
Material Selection ◽  
Dissimilar Materials ◽  
Analytical Description ◽  
Density Field ◽  
Aggregation Scheme ◽  
Position And Orientation ◽  
Geometry Projection ◽  
Size Variable ◽  
Selection Of

We present a new method for the simultaneous topology optimization and material selection of structures made by the union of discrete geometric components, where each component is made of one of multiple available materials. Our approach is based on the geometry projection method, whereby an analytical description of the geometric components is smoothly mapped onto a density field on a fixed analysis grid. In addition to the parameters that dictate the dimensions, position, and orientation of the component, a size variable per available material is ascribed to each component. A size variable value of unity indicates that the component is made of the corresponding material. Moreover, all size variables can be zero, signifying the component is entirely removed from the design. We penalize intermediate values of the size variables via an aggregate constraint in the optimization. We also introduce a mutual material exclusion constraint that ensures that at most one material has a unity size variable in each geometric component. In addition to these constraints, we propose a novel aggregation scheme to perform the union of geometric components with dissimilar materials. These ingredients facilitate treatment of the multi-material case. Our formulation can be readily extended to any number of materials. We demonstrate our method with several numerical examples.

Sequential Roundoff for Improving Robot Position Accuracy

1995 ◽  
Author(s):  
Zhiming Ji
Keyword(s):  
Numerical Analysis ◽  
Inverse Kinematics ◽  
Positioning Accuracy ◽  
Actual Position ◽  
Position Accuracy ◽  
Roundoff Errors ◽  
Position And Orientation ◽  
End Effectors ◽  
Robot Position ◽  
Selection Of

Abstract A robot can only reach discrete locations within its workspace due to its finite encoder counts. Actual position and orientation reached by end-effectors are therefore the result of roundoff in the encoder counts. Traditionally the roundoff is carried out at the end of inverse kinematics, which produces the propagation and accumulation of the roundoff errors (except for Cartesian type of robot). We proposed a sequential roundoff procedure during the inverse kinematics process to compensate the roundoff errors. Numerical analysis shows that this method can lead to significant improvement in the positioning accuracy. Our study also shows that the sequence with which the inverse is carried out affects the improvement. Selection of sequence for inverse kinematics is discussed.

Position-Based Visual Servoing of a Mobile Robot with an Automatic Extrinsic Calibration Scheme

Robotica ◽  
2019 ◽  
Vol 38 (5) ◽  
pp. 831-844 ◽  
Author(s):  
Radhe Shyam Sharma ◽  
Santosh Shukla ◽  
Laxmidhar Behera ◽  
Venkatesh K. Subramanian
Keyword(s):  
Mobile Robot ◽  
Gradient Descent ◽  
Visual Servoing ◽  
Sliding Mode ◽  
Single Experiment ◽  
Novel Approach ◽  
Position And Orientation ◽  
Estimation And Control ◽  
Adaptive Nature ◽  
And Control

SUMMARYIn this paper, we present and implement a novel approach for position-based visual servoing. The challenge of controlling the mobile robot while simultaneously estimating the camera to mobile robot transformation is solved. This is achieved using gradient descent (GD)-based estimation and the sliding-mode approach. The GD approach allows online parameter estimation for controlling the robot to achieve a desired position and orientation. The adaptive nature of the parameters demonstrates the robustness of the system. In contrast to existing work, the proposed technique achieves both estimation and control tasks in a single experiment. Simulation and experimental results are provided to validate the performance of the proposed scheme.

A General Formula of Degree of Freedom for Parallel Mechanisms

2008 ◽  
Author(s):  
Ting-Li Yang ◽  
Dun-Jin Sun
Keyword(s):  
General Formula ◽  
Screw Theory ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Characteristic Equations ◽  
Position And Orientation ◽  
Symbolic Operation ◽  
Selection Of

In this paper, a general formula of degree of freedom (DOF) for parallel mechanisms has been presented which could provide the full-cycle DOF. The key parameters in the formula can be determined via the position and orientation characteristic equations and their symbolic operations of serial and parallel mechanisms proposed by author and the symbolic operation is simple. It is totally different from the methods based on screw theory and based on displacement subgroup. The formula has been used for selection of driving pairs and determination of idle pairs. The formula may also be used for determining the DOF of other multi-loop mechanisms besides parallel mechanisms.

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